Automatic induction regulator for arc and ore furnaces and similar automatic purposes



Nov. 30, 1943. Y. E. EFRAIMOVITCH 3 AUTOMATIC INDUCTION REGULATOR FORARC AND ORE FURNACES AND SIMILAR AUTOMATIC PURPOSES Filed March 18,11.94:]. 2 Sheets-Sheet 1 Efhszz'mowfck .Nov. 30, 1943. Y. E.EFRAIMOVITCH 2,335,399

AuToMATIc INDUCTION REGULATOR FOR ARC AND ORE FURNACES AND SIMILARAUTOMATIC PURPOSES v Filed March 18, 1941 2 Sheets-Sheet 2 RST 45Patented Nov. 30, 1943 AUTOMATIC INDUCTION REGULATOR FOR ARC AND OREFURNACES AND SIMILAR AUTOMATIC PURPOSES Yuri Efimovitch Efraimovitch,Moscow, ',Union of Soviet Socialist Republics Application March 18,1941, Serial No. 384,018. In the Union of Soviet Socialist RepublicsApril 4 Claims. (CI. 13-13) This invention is a continuation in part ofapplication Serial No. 267,494 filed April 12, 1939.

Existing systems of automatic regulators for the regulation of arcfurnaces possess low sensitiveness and insufficiently smooth change ofspeed when shifting the electrodes; there is also present lack ofdependence between this speed and the magnitude of irregularity in thefurnace operation. More perfect regulators use very complicated andexpensive apparatus and a great number of motors (in some occasionsattaining 8 motors with three phase furnaces).

In the present invention the number of revolutions of the motor which isto shift the electrode shows direct dependence on the magnitude ofirregularity in the furnace operation. A particular construction of thecontrol member, which is to perceive the irregularities of the furnaceoperation achieves high sensibility of the entire device.

In the adjoined drawings Fig. 1 shows a theoretical diagram of thecontrol member Fig. 2 shows an elevational view of the control memberFig. 3 is a perspective view of the regulator in its essential twoparts-the control member and the tailing system.

Fig. 4 illustrates an exemplary scheme of electrical connections adaptedto the regulation of one phase of the electric furnace.

The control member consists of an aluminium disc 5 penetrated by thefluxes of three magnetic circuits A, B and C (Fig. 1).

On the shaft of the control member (see Fig. 3) is fastened thereversing switch 6 connected to the contactors of the motor whichperforms the lifting and lowering of the electrode (neither thecontactors nor the motor are shown on Fig. 3). Two spiral springs IS,the tension of which can be regulated, tend to hold the control memberin its initial position and to react against the moment of rotationcreated by the coils A, B and C.

The resistor 28 is intended to increase or decrease th resistances inthe rotor circuit of the motor serving to shift the electrode. In orderto follow exactly the movements of the control member the shaft 22 ofthe resistor 20 is linked to the shaft 23 of the control member by meansof a tailing system. This latter consists of three bevel gears l, 8 and9, the first of which is fastened on the shaft of the control member.Bevel gear 9 is fixed on the shaft of the resistor 20; the position ofthe third bevel gear 8 which is freely revoluble 0n the extension of theshaft 22 is determined by the position of bevel gears l and 9; thisthird bevel gear is terminated by the pin 2|, which grips the fork ofthe reversing switch M. The shaft 23 is located with one of its ends inthe shaft 22 as in a bearing and can freely rotate in it.

The sliders 0f the resistor 20 represent three brushes having mutualelectrical interconnections.

The reversing switch [4 starts the motor It in either direction, wherebya rotation of the shaft of the resistor 20 and a corresponding movementof contacts of the resistor results, this shaft being driven by the wormgear l!l8, fixed on the shaft of the motor [6.

On Fig. 4 is shown an exemplary electrical scheme of the regulator, setfor one phase of the furnace, as in the arc furnace l with threeelectrodes the motor 12 regulates only one electrode. The furnacetransformer 2 is fitted with a reversing switch 3 which performs theoverswitching of the high-tension winding from delta to star; blockingcontacts are fixed on the shaft of this reversing switch 3 and serve tostart the control member accordingly to the disturbances in the normaloperation of the furnace. The windings on the coils ofthe control memberare correspondingly energized: coil A from the arc tension, coil from acurrent transformer of the same phase, coil C from an outside source ofenergy. The resistances in circuit of the coils A and B and capacitiesin circuit 01' the coil B, shown in Fig. 4 are chosen so as to make thecurrents in coils A and B equal and coinciding in phase. By means or thelow powered trans formeri and the blocking contacts of the switch 3there is created an artificial phase-displacement of Bu between thehuxes of winding 0 and the windings of A and B.

The motor iii 15 started in either direction by means of the tailingsystem I, 8, and H and the reversing switch it, its rotation beingtransmitted to the resistor 20 through the worm-gear lt-i8, whereby themagnitude of resistances, inserted in the chain of the rotor of themotor I2, is correspondingly modified.

The cohtactors it and i I are provided to secure the starting of themotor IE or correspondingly to brake it after the regulating process hasreached its end.

Both outer contacts on the right side of 10 (on Fig. 4) serve to switchout a part of the resistances in resistor 2:3 when the motor I2 isstarting to lift the electrode.

Both reversing switches l3 fixed on the shaft of th motor l2 shown onlyin Fig. 4 and IS on the shaft of the resistor 20 are connected in a wellknown scheme to the purpose of switching the motor [2 over to braking bycounter current and to control of this braking after the regulatingprocess has come to an end.

The system is connected to an outer net by means of the switch 2!.

By adding correspondingly simple devices the proposed system ofautomatic regulation could easily perform the electrode shifting by handoperation.

The action of the device is as follows:

To the first part of the described device .(control member) 5 withspring l9 and reversing switch 6 movement is imparted when a disturbancein the normal working conditions of a phase of the furnace inducescorresponding alterations of the current in the coil windings A and B ofthe control member; the interaction of the fluxes of these coils withthe currents induced in the disc by the coil winding creates a moment onthe axis of disc 5, which forces the disc to turn by an angle which isproportional to the magnitude of the occurred disturbances, themagnitude of the angle of revolution being regulated by the tension ofspring I9. (It is understood that during normal operating conditions themoment on the axis of the control member equals zero.) The turning ofthe control member closes the corresponding contacts of the reversingswitch 6. This is accompanied by the on switching of contactor It or ll,which in turn start the motor [2 in the corresponding direction, wherebythe electrode is lifted or lowered.

The second part of the proposed device is intended to regulate the speedof the shifting of the electrode according to the magnitude of theoccurred disturbance in normal operating conditions and Worksas'follows: 1

The bevel gear 7. coupled to the shaft'of the control member 5 is turnedsimultaneously with the rotation of this latter, and-carries along bevelgear 8, which by means of its pin closes the corresponding contacts ofthe reversing switch Ml. Until this moment the bevel gear 9, rigidlyfixed on the shaft of the resistor ZEland this shaft are motionless. Thereversing switch it starts the motor E6 in the corresponding directionand the shaft of the resistor with the bevel gear 9 is driven intomotion by means of the worm gear l.'l.i8; bevel gear 9 rotates in adirection opposite to that of the bevel gear 'i' and thereby bringsgear8 and reversing switch i l to their initial position. The entire processas described is based upon the scheme of connection of the motor to andthe reversing switch it; this is worked in such a manner that when gear1 is started in one direction, it so closes the reversing switches 14that the third gear Swill be rotated by the motor It in an oppositedirection, which will result in an off-switching of Hi, bringing forthastoppage of motor I5.

The following movements of the control memher 5., characteristic as tothe gradual restora-. tion of normal conditions in the regulated phase,will cause a gradual restoring of the shaft of resistor 29 in itsinitial position, during which this shaft will exactly repeat theshifting of the. shaft of control member 5 according to the already de-.scribed performance. It is to be noted thatthe invention may be bestunderstood on reference to Figures 3 and 4, wherein the electrodeshifting through actuation of the contactors l0 and H. The contactors Itand H are energized selectively by means of the switch 6. The importantfeature of the invention relates to the diiferential gear mechanismformed by the gears l, 8 and 9 and in which the planet gear 8 is movedwhen the gear 9 remains sttaionary and when the gear 7 is rotated tostart the motor it which thereafter rotates the gear 9 to open thecircuit to the motor l2 through the switch 55 and to restore the planetgear 8 to its original position and to vary the resistor 26 to adjustthe speed of the motor.

The present automatic regulator as described possesses high sensibilityowing to the ingenious construction of the control member and isresponsive to the requirements of a smooth dependence between the speedof electrode shifting and the magnitude of disturbances in the normalworking condiitons of the furnace, this feature being achieved by theaction of the described tailing system, which exactly transmits themove-. ments of the control member to the speed regulating device of theelectrode shifting motor.

Having thus described the invention and the mode of its performance whatI claim is:

1. In apparatus for automatically shifting an electrode of an arcfurnace, .a motor for shifting said electrode, a rotatable shaft,yieldable means tending to maintain said shaft in a neutral position,means responsive toa disturD nCe of the normal electrical.characteristics of thearc furnace for rotating said shaft from theneutral position,,m eans including a reversingswitch actuateduponrotation of said shaft for startingsaid motor, a gear driven bysaid. shaft, a second shaft normally fixed against rotation, a secondgear.

connected to; the second shaft, a planet gear wheel meshing with saidgears so as to swing upon rotation of the first shaft, a second motorfor rotating the second shaft, means including a reversing switch forstarting the second. motor upon swinging of the planet gear, and movablemeans actuated by rotation of the second .shaft for adjusting the speedof the first motor.

2; An automaticregulator for electric. arc furnaces comprising. controlmeans including a.ro.-. tatable control part and coils ofthreeelectromagnetic circuitsfor rotating said rotatable part, thewindings of said coilsbeing. energized from the current of one phase of.the arc. furnace, from Voltage. of the same. phase. andfrom. an outsidesource, spring. means. normally tending to hold the rotatable part ofsaid controlmeans in a neutral position, an electrode regulating motor,a reversingv switch on the, rotatable part. of. said control. means andoperable to. start. the electrode regulating motor. in either direction,movable. means for adjusting the speed otsaid motor, and means operatedin dependence. upon rotation .ofv said rotatablev control part formovingsaid ad-. justing. means in degree proportional to the. extent of.rotary movement of saidrotatable part.

3. An automatic regulator for electric arc, fur: naces.v comprisingcontrol means. including a, rotatable disc and. coils of threeelectromagnetic, circuits. for rotating. said. disc, the. windings of;said coils being energized. from the current. of one, phase of the arcfurnace, from voltage of the; same phase and from an outside source,oppoa sitelyacting springs normally tending to. hold the rotatable discof said control means in a neu-.. tral position, an electrode regulatingmotor, a. reversing sw t h op ra l y saiddhcs to. star motor 12 isstarted by rotationuof the disc 5. 7 5,v the. electrode regulatingrnptorin either direca tion, movable means for adjusting the speed ofsaid motor, and means operated in dependence upon rotation of saidrotatable disc for moving said adjusting means in degree proportional tothe extent of rotary movement of said disc.

4. An automatic regulator for electric arc furnaces comprising controlmeans including a rotatable control part and coils of threeelectromagnetic circuits for rotating said rotatable part, the windingsof said coils being energized from the current of one phase of the arcfurnace, from voltage of the same phase and from an outside source,spring means normally tending to hold the rotatable part of said controlmeans in a neutral position, an electrode regulating motor, a

reversing switch on the rotatable part of said control means andoperable to start the electrode regulating motor in either direction,and a device for adjusting the speed of the motor, said device includinga resistor connected with the regulating motor, a gear wheel driven bythe rotatable control part, a second gear wheel connected with saidresistor, a, third gear wheel meshing with each of the two firstmentioned gear wheels, an auxiliary motor, a reversing switchcontrolling said auxiliary motor and operable by said third gear wheel,and a driving connection between said auxiliary motor and said resistorfor moving said resistor in degree proportional to the extent of rotarymovement of said rotatable part.

YURI EFIMOVITCH EFRAIMOVITCH.

